A number of methods are known in the prior art for producing optical lenses with diffractive surfaces. Plastic optics with diffractive surfaces have been generated through diamond turning operations where a diamond tool is used to cut the optical material. This method, or variations thereof, is discussed in European Patent Application 557,057 A1, in an article entitled "Athermalization of a Single-Component Lens with Diffractive Optics" which appeared in the May 1993 issue of Applied Optics, in an article entitled "Coproduction of Kinoforms by Single Point Diamond Machining" which appeared in the December 1989 issue of Optics News and in a paper entitled "Diffractive Optical Elements in Flir" which was presented at the 3rd International Conference on Holographic Systems, Components and Applications in September of 1991.
Another method for producing optical lenses with diffractive surfaces is discussed in a paper entitled "Spherical Grating Objective Lenses for Optical Disk Pick-ups" which appeared in Volume 26 of the Japanese Journal on Applied Physics in 1987. Such article discusses that for the use of a computer and numeric controlled machining technique, blazed grating dyes are generated using diamond turning lathes. These blazed grating dyes are, in turn, used to mold grating collimator lenses through plastic injection molding.
U.S. Pat. No. 5,161,057 to Johnson teaches that a molding tool for molding a fresnel lens which includes a transmission grating used to reduce chromatic aberration wherein the molding tool would typically be formed by a precision turning operation using a straight edge, single-crystal diamond cutter to define the grating facet surfaces.
U.S. Pat. No. 5,589,983 to Meyers et al teaches a method for manufacturing a diffractive surface profile wherein a specific technique for diamond turning the molding elements is taught for injection molding of optical lenses with diffractive surfaces.
The use of diffractive surfaces in optical instruments is growing as is evidenced by the inclusion of the ability to design them in a variety of major commercial design software programs. The utility of diffractive surfaces is greatly enhanced if such surfaces can be produced in high volume. For plastic optics, this is readily achievable with existing technology. By single-point-diamond turning a nickel-coated steel tool, one can use standard plastic injection molding fabrication techniques to produce diffractive-surface parts in high volumes. However, it has been noticed on many occasions that nickel tooling which has been turned for aspheric surfaces is not as robust as the traditional steel tooling for spherical surfaces. This difference in wear and damage potential becomes even greater considering the fine structure required for diffractive surfaces.